1. Field of the Invention
The present invention relates generally to data routing. More particularly, the invention relates to systems and methods for distributed data routing in a wireless network.
2. Description of Related Art
WiMax (Worldwide Interoperability for Microwave Access) is a wireless broadband technology, which supports point to multi-point (PMP) broadband wireless access. WiMAX™ is based upon the IEEE 802.16 standard enabling the delivery of wireless broadband services. WiMAX products can accommodate fixed and mobile usage models. The IEEE 802.16 standard was developed to deliver non-line-of-sight (LoS) connectivity between a subscriber station and base station with typical cell radius of three to ten kilometers.
All base stations and subscriber stations claiming to be WiMAX compliant must go through a rigorous WiMAX Forum Certified™ testing process. WiMAX Forum Certified systems can be expected to deliver capacity of up to 40 Mbps per channel. This is enough bandwidth to simultaneously support hundreds of businesses with T-1 speed connectivity and thousands of residences with DSL speed connectivity. The WiMAX Forum expects mobile network deployments to provide up to 15 Mbps of capacity within a typical cell radius of up to three kilometers. WiMAX technology already has been incorporated in notebook computers and PDAs to deliver high speed mobile Internet services.
One of the advantages of WiMAX technology is the use of Orthogonal Frequency-Division Multiplexing (OFDM) over Edge, CPRS, or HSPA to deliver higher bandwidth efficiency, and, therefore, higher data throughput, with more than one Mbps downstream and higher data rates. Adaptive modulation also increases link reliability for carrier-class operation and the possibility to keep higher order modulation at wider distance extend full capacity over longer distances.
OFDM is a digital encoding and modulation technology. It has been used successfully in wire-line access applications, such as Digital Subscriber Line (DSL) modems and cable modems as well as WiFi. Products from WiMAX Forum member companies often use OFDM-based 802.16 systems to overcome the challenges of non-line-of-sight (NLoS) propagation. OFDM achieves high data rate and efficiency by using multiple overlapping carrier signals instead of just one. All future technologies for 4G will be based upon OFDM technology.
Orthogonal Frequency Division Multiple Access (OFDMA) is enhanced OFDM and is used in Mobile WiMAX technology and the IEEE 802.16e-2005 standard. It is a multi-user version of Orthogonal Frequency-Division Multiplexing (OFDM). The difference between the two technologies is that OFDMA assigns subsets of sub-carriers to individual users allowing simultaneous low data rate transmission from several users.